Global Illumination Research Articles

Combined volume and surface rendering with global illumination caching

We present a combined volume and surface rendering technique with global illumination caching. Our approach uses volumetric path tracing to compute the global illumination volume and local shading models for rendering the isosurface. By joining both visualization approaches, we have enhanced the display and illumination of the surfaces while preserving physically realistic illumination of the participating media. To achieve real-time performance and avoid recomputing the image when the camera view changes, we compute the global illumination volume incrementally and defer the projection to a later step. We evaluated our technique by comparing different local shading models for isosurface rendering with the result of full volumetric path tracing and with the non-caching variant of our technique. Results show that the caching and non-caching variants perform comparably well, while the caching variant has the added benefit of being camera-view-independent. Additionally, we show that our approach emphasizes the surfaces within volumes better than volumetric path tracing.

Reconstruction of radiance field with neural network for real-time rendering

Fast global illumination methods has been one of the most exiting area of rendering because it could solve many industrial problems of achieving balance between realistic rendering and stable frame rate. So this study employs a neural network to learn a radiance field from the distribution of a particular group of objects by reconstructing a 3D radiance field using spherical harmonics and neural networks. The network learned the estimated radiance distribution in space by voxel data and creating a hash grid containing information from spherical harmonics. This research also provided a new simplified light transition function that emulated the behavior of light in a specific scene, as global illumination could be broken down into a sequence of the light transport progress. It may be possible to see how the light changes throughout a 3D environment by computing the global GI using this multiple-ray bounce model.

Importance-Based Ray Strategies for Dynamic Diffuse Global Illumination

In this paper, we propose a first and efficient ray allocation technique for Dynamic Diffuse Global Illumination (DDGI) using Multiple Importance Sampling (MIS). Our technique, IS-DDGI, extends DDGI by incorporating a set of importance-based ray strategies that analyze, allocate, and manage ray resources on the GPU. We combine these strategies with an adaptive historical and temporal frame-to-frame analysis for an effective reuse of information and a set of GPU-based optimizations for speeding up ray allocation and reducing memory bandwidth. Our IS-DDGI achieves similar visual quality to DDGI with a speedup of 1.27x to 2.47x in total DDGI time and 3.29x to 6.64x in probes ray tracing time over previous technique [Majercik et al. 2021]. Most speedup of IS-DDGI comes from probes ray tracing speedup.

Deep polyp image enhancement using region of interest with paired supervision

Endoscopic medical imaging in complex curved intestinal structures are prone to uneven illumination, low contrast and lack of texture information. These problems may lead to diagnostic challenges. This paper described the first supervised deep learning based image fusion framework to enable the polyp region highlight through a global image enhancement and a local region of interest (ROI) with paired supervision. Firstly, we conducted a dual attention based network in global image enhancement. The Detail Attention Maps was used to preserve more image details and the Luminance Attention Maps was used to adjust the global illumination of the image. Secondly, we adopted the advanced polyp segmentation network ACSNet to obtain the accurate mask image of lesion region in local ROI acquisition. Finally, a new image fusion strategy was proposed to realize the local enhancement effect of polyp image. Experimental results show that our method can highlight the local details of the lesion area better and reach the optimal comprehensive performance with comparing with 16 traditional and state-of-the-art enhancement algorithms. And 8 doctors and 12 medical students were asked to evaluate our method for assisting clinical diagnosis and treatment effectively. Furthermore, the first paired image dataset LHI was constructed, which will be made available as an open source to research communities.

The Potential of Dye Synthesize Solar Cells for Mitigation Of Carbon (Iv) Oxide Emissions

World is experiencing rapid commercial growth and urbanization. Carbon (IV) oxide (CO2) emissions into the atmosphere is increasing. As a result, a more effective energy policy is required. As a matter of fact, sustainable environmental quality has been identified as a critical component of long-term economic development success. Many studies have found that lower CO2 emissions are an indicator of improved environmental quality. In the future, low-cost photoelectric technologies with superior sun-to-energy power conversion efficiency, extended lifetime, and low toxicity may replace conventional silicon-based solar panels and provide effective global illumination. Dye-sensitized solar cells (DSSCs) based on the zinc oxide nanorods are capable of all the aforementioned features. Zinc-oxide (ZnO) nanostructures are important for dye synthesis solar cells, and it is a leading semiconductor that researchers are interested in. The primary objective/purpose of this resarch is to highlight impact of carbon (IV) oxide and the potential of DSSC for reducing CO2 discharges into the atmosphere. Method of ZnO NRs deposition on seed layer coated FTO Glass by Hydrothermal method was also expounded. The morphology of nanorods is presented, based on the available literature it concludes that the production of efficient DSSCs can reduce reliance on fossil fuels, which are the agent of ozone depletion layer due to green gas emissions.

Optogenetic termination of atrial tachyarrhythmias by brief pulsed light stimulation

AimsThe most efficient way to acutely restore sinus rhythm from atrial fibrillation (AF) is electrical cardioversion, which is painful without adequate sedation. Recent studies in various experimental models have indicated that optogenetic termination of AF using light-gated ion channels may provide a myocardium-specific and potentially painless alternative future therapy. However, its underlying mechanism(s) remain(s) incompletely understood. As brief pulsed light stimulation, even without global illumination, can achieve optogenetic AF termination, besides direct conduction block also modulation of action potential (AP) properties may be involved in the termination mechanism. We studied the relationship between optogenetic AP duration (APD) and effective refractory period (ERP) prolongation by brief pulsed light stimulation and termination of atrial tachyarrhythmia (AT). Methods and resultsHearts from transgenic mice expressing the H134R variant of channelrhodopsin-2 in atrial myocytes were explanted and perfused retrogradely. AT induced by electrical stimulation was terminated by brief pulsed blue light stimulation (470 nm, 10 ms, 16 mW/mm2) with 68% efficacy. The termination rate was dependent on pulse duration and light intensity. Optogenetically imposed APD and ERP changes were systematically examined and optically monitored. Brief pulsed light stimulation (10 ms, 6 mW/mm2) consistently prolonged APD and ERP when light was applied at different phases of the cardiac action potential. Optical tracing showed light-induced APD prolongation during the termination of AT. ConclusionOur results directly demonstrate that cationic channelrhodopsin activation by brief pulsed light stimulation prolongs the atrial refractory period suggesting that this is one of the key mechanisms of optogenetic termination of AT.

Lyophilization-Free Approach to the Fabrication of Conductive Polymer Foams Enabling Photo-Thermo-Electrical-Induced Cell Differentiation under Global Illumination

In this study, we fabricate conductive polymer (PEDOT:PSS) foams with tunable density and mechanical properties via a new and efficient lyophilization-free method and use asymmetric acid treatment to create a PEDOT:PSS scaffold with asymmetric light absorptivity, which helps generate the asymmetric photo-thermo-electrical conversion under simple global illumination. Distinct light absorptivity along the scaffold has been proved to be related to the different doping states via asymmetric acid treatment. Such noninvasive photo-thermo-electrical stimulation significantly induces the expressions of genes related to neural differentiation under an illumination intensity of 240 mW/cm2 for only 30 min. This research will not only provide a new approach to fabricate conductive polymer foams via the lyophilization-free method but also enable the global illumination to provoke the photo-thermo-electrical effect of conductive polymers with asymmetric light absorptivity for thermoelectric conversion and biomedical potential applications in tissue engineering for therapeutic purposes.

Pd quantum dot induced changes in the photocatalytic, electrocatalytic, photoelectrochemical and thermoelectric performances of galvanically synthesized Sb2Se3 thin films

We present a novel solution-based galvanic (electrochemical) synthesis of antimony selenide light absorber thin films on FTO (Fluorine doped tin oxide) coated glass substrates. The structural, surface morphological, compositional, optical and electrical properties of the samples were characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Fast Fourier Transform (FFT), Energy Dispersive X-ray spectroscopy (EDS), UV–Vis and Photoluminescence (PL) spectroscopy and Electrochemical Impedance spectroscopy (EIS). X-ray Photoelectron Spectroscopy (XPS) was employed to determine the elemental state composition of as-deposited and annealed Sb2Se3 films containing Pd. The annealed Sb2Se3:Pd films exhibited hydrogen evolution in neutral buffer medium with small potential of 164 mV and a Tafel slope of 39 mV/decade. Pd incorporation enhances the efficiency towards HER performance, which shows the 10 mAcm−2 current density at a low overpotential of 244 mV with reasonable durability. Photoelectrochemical (PEC) water splitting was observed at a potential of 0.41 V versus a reversible hydrogen electrode (RHE) with 3.2 mA cm−2 at 0 V versus RHE, under air mass 1.5 global illumination in a neutral electrolyte. To check the performance of this material for waste water treatment photodegradation of hazardous dyes and metal ion reduction experiments were performed. The photodegradation percentages of MG, MB and RhB dyes with annealed Sb2Se3:Pd thin film catalysts and H2O2 were 99.32% in 10 min, 98.95% in 20 min and 99.16% in 30 min, respectively. Cu2+ ions were photocatalytically reduced with the same catalyst to an extent of 98.9% in 20 min. Thermoelectric measurements on annealed Sb2Se3:Pd yielded the best Figure of merit and power factor values of 39.8 μW/cmK2 and 10.81 × 10−3, respectively at 373 K.

Hydroxycinnamic acid derivatives for UV-selective and visibly transparent dye-sensitized solar cells

Naturally abundant dyes are very attractive for the development of dye-sensitized solar cells (DSSCs). Hydroxycinnamic acid derivatives, such as caffeic acid (CA), ferulic acid (FA), and p-coumaric acid (PA), were considered for the selective harvesting of ultraviolet A (UVA) (315–400 nm) photons. Their spectroscopic and electrochemical properties were investigated both theoretically and experimentally. They were further successfully adopted as photosensitizers in UV-selective and visibly transparent DSSCs, which exhibited a power conversion efficiency of 0.22–0.38% under AM (air mass) 1.5G (global) illumination (100 mW/cm2) and 3.40–3.62% under UVA irradiation (365 nm, 115.22 mW/cm2), with a corresponding visible light transmittance (VLT) of 49.07–43.72% and a general color rendering index (Ra) of 93–90.

Virtual Light Sensing Technology for Fast Calculation of Daylight Autonomy Metrics.

Virtual sensing technology uses mathematical calculations instead of natural measurements when the latter are too difficult or expensive. Nowadays, application of virtual light sensing technology becomes almost mandatory for daylight analysis at the stage of architectural project development. Daylight Autonomy metrics should be calculated multiple times during the project. A properly designed building can reduce the necessity of artificial lighting, thus saving energy. There are two main daylight performance metrics: Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). To obtain their values, we have to simulate global illumination for every hour of the year. A light simulation method should therefore be as efficient as possible for processing complex building models. In this paper we present a method for fast calculation of Daylight Autonomy metrics, allowing them to be calculated within a reasonable timescale. We compared our method with straightforward calculations and other existing solutions. This comparison demonstrates good agreement; this proves sufficient accuracy and higher efficiency of the method. Our method also contains an original algorithm for the automatic setting of the sensing area. The sDA metric is calculated considering blinds control, which should open or close them depending on overexposure to direct sunlight. Thus, we developed an optimization procedure to determine the blinds configuration at any time.

An Analysis of Real-Time Measured Solar Radiation and Daylight and Its Energy Implications for Semi-Transparent Building-Integrated Photovoltaic Façades

For analyzing cooling loads, day-lighting, and building-integrated photovoltaic (BIPV) systems, solar radiation and daylight illuminance data are required. However, these data are sparse. Furthermore, studies have shown that the energy potential of building-integrated photovoltaic (BIPV) systems for the entire building skin (BS) and unconventional orientations, such as east, west, and north need further exploration. Thus, this study presents findings from measured solar data and an energy analysis of semi-transparent BIPV. Firstly, solar radiation and daylight data measured from June 2019 to May 2020 in Hong Kong are presented. The analyzed solar-radiation data were used to determine the solar-energy potential of BIPV for BS and the four principal building orientations (i.e., N, E, S and W). With a simple analytical approach, the solar data’s building-energy implications for semi-transparent BIPV were assessed. The findings showed that the annual average horizontal global-, diffuse-, and direct-irradiance values were 291.8, 164.3, and 127.5 W/m2/day, respectively. Similarly, 120, 72, and 107 klux were obtained as the peak global, diffuse, and direct illuminance, respectively. Furthermore, the results show the potential of using BIPV on the entire BS in Hong Kong. It was also observed that a semi-transparent BIPV façade integrated with daylight-linked lighting controls could offer significant energy savings in electric lighting and cooling while also producing energy. In particular, BIPV façades with a large window-to-wall ratio (WWR) of 80% can provide an overall energy benefit of up to 7126 kWh.

Local Adaptive Illumination-Driven Input-Level Fusion for Infrared and Visible Object Detection

Remote sensing object detection based on the combination of infrared and visible images can effectively adapt to the around-the-clock and changeable illumination conditions. However, most of the existing infrared and visible object detection networks need two backbone networks to extract the features of two modalities, respectively. Compared with the single modality detection network, this greatly increases the amount of calculation, which limits its real-time processing on the vehicle and unmanned aerial vehicle (UAV) platforms. Therefore, this paper proposes a local adaptive illumination-driven input-level fusion module (LAIIFusion). The previous methods for illumination perception only focus on the global illumination, ignoring the local differences. In this regard, we design a new illumination perception submodule, and newly define the value of illumination. With more accurate area selection and label design, the module can more effectively perceive the scene illumination condition. In addition, aiming at the problem of incomplete alignment between infrared and visible images, a submodule is designed for the rapid estimation of slight shifts. The experimental results show that the single modality detection algorithm based on LAIIFusion can ensure a large improvement in accuracy with a small loss of speed. On the DroneVehicle dataset, our module combined with YOLOv5L could achieve the best performance.

Темпоральный алгоритм излучательности для 3D-сцен произвольной детализации

In this paper, we propose an approach for calculating global illumination by the radiosity method that allows achieving high performance for a large number of patches involved in the calculations. Two key ideas of the proposed approach are the creation of proxy geometry based on axis-aligned virtual patches and the method of temporal radiosity, which uses the interpretation of form-factors in terms of probabilities. The combination of the proposed methods makes it possible to obtain a rapid update of global illumination for light sources changing their positions with image quality close to the naive radiosity method.

Does Thermal Really Always Matter for RGB-T Salient Object Detection?

In recent years, RGB-T salient object detection (SOD) has attracted continuous attention, which makes it possible to identify salient objects in environments such as low light by introducing thermal image. However, most of the existing RGB-T SOD models focus on how to perform cross-modality feature fusion, ignoring whether thermal image is really always matter in SOD task. Starting from the definition and nature of this task, this paper rethinks the connotation of thermal modality, and proposes a network named TNet to solve the RGB-T SOD task. In this paper, we introduce a global illumination estimation module to predict the global illuminance score of the image, so as to regulate the role played by the two modalities. In addition, considering the role of thermal modality, we set up different cross-modality interaction mechanisms in the encoding phase and the decoding phase. On the one hand, we introduce a semantic constraint provider to enrich the semantics of thermal images in the encoding phase, which makes thermal modality more suitable for the SOD task. On the other hand, we introduce a two-stage localization and complementation module in the decoding phase to transfer object localization cue and internal integrity cue in thermal features to the RGB modality. Extensive experiments on three datasets show that the proposed TNet achieves competitive performance compared with 20 state-of-the-art methods. The code and results can be found from the link of <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://rmcong.github.io/proj_TNet.html</uri> .

Electrical passivation of III-V multijunction solar cells with luminescent coupling effect

Perimeter recombination is one of the causes identified for having a nonuniform luminescent coupling effect in III-V multijunction solar cells. A potential solution could be the electrical passivation of the multijunction solar cell perimeter. To test this hypothesis, electrical passivation of InGaP/GaAs/Ge 3-junction solar cells was done by the atomic layer deposition of thin Al 2 O 3 films. Perimeter passivation of a 3-junction solar cell relatively increased current collection measured at luminescent coupling and direct subcell excitation by as much as 11.4% and 29.8%, respectively. Meanwhile, the current homogeneity improved relatively by as much as 7.9% after electrical passivation. At 1-sun global standard illumination (AM 1.5G), 0.2% absolute conversion efficiency increase was achieved. Therefore, electrical passivation of fully working III-V multijunction solar cells is a non-invasive, post-treatment process that can recover losses due to surface defects caused by oxidation. • Post-treatment passivation for fully working multijunction solar cell. • Larger conversion efficiencies in multijunction solar cells with smaller active areas. • Spatial current uniformity improvement after perimeter passivation. • Reduction of shunt leakage current in a subcell made of indirect bandgap material. • Alleviate lateral resistance effects by electrical passivation.

LOV2-based photoactivatable CaMKII and its application to single synapses: Local Optogenetics.

Optogenetic techniques offer a high spatiotemporal resolution to manipulate cellular activity. For instance, Channelrhodopsin-2 with global light illumination is the most widely used to control neuronal activity at the cellular level. However, the cellular scale is much larger than the diffraction limit of light (<1 μm) and does not fully exploit the features of the "high spatial resolution" of optogenetics. For instance, until recently, there were no optogenetic methods to induce synaptic plasticity at the level of single synapses. To address this, we developed an optogenetic tool named photoactivatable CaMKII (paCaMKII) by fusing a light-sensitive domain (LOV2) to CaMKIIα, which is a protein abundantly expressed in neurons of the cerebrum and hippocampus and essential for synaptic plasticity. Combining photoactivatable CaMKII with two-photon excitation, we successfully activated it in single spines, inducing synaptic plasticity (long-term potentiation) in hippocampal neurons. We refer to this method as "Local Optogenetics", which involves the local activation of molecules and measurement of cellular responses. In this review, we will discuss the characteristics of LOV2, the recent development of its derivatives, and the development and application of paCaMKII.

Динамика Ланжевена в стохастической трассировке лучей: вычислительные эксперименты

The main computationally extensive task of realistic computer graphics is the calculation of global illumination. The work investigates the speed of the convergence of lighting simulation using Monte Carlo integration based on the Langevin equation. The paper presents the third part of the study. It describes the computational experiments performed with various modifications of the method. Based on the analysis of the results, it was concluded that the preconditioning matrix, which does not require calculation of the gradient of the potential, has the greatest importance for convergence. This allows one to significantly accelerate calculations.

Examining the utility of a photorealistic virtual ear in otologic education

BackgroundOtolaryngology–head and neck surgical (OHNS) trainees’ operating exposure is supplemented by a combination of didactic teaching, textbook reading, and cadaveric dissections. Conventional teaching, however, may not adequately equip trainees with an understanding of complex visuospatial relationships of the middle ear. Both face and content validation were assessed of a novel three-dimensional (3D) photorealistic virtual ear simulation tool underwent face and content validation as an educational tool for OHNS trainees.MethodsA three-dimensional mesh reconstruction of open access imaging was generated using geometric modeling, which underwent global illumination, subsurface scattering, and texturing to create photorealistic virtual reality (VR) ear models were created from open access imaging and comiled into a educational platform. This was compiled into an educational VR platform which was explored to validate the face and content validity questionnaires in a prospective manner. OHNS post-graduate trainees were recruited from University of Toronto and University of Calgary OHNS programs. Participation was on a voluntary basis.ResultsTotal of 23 OHNS post-graduate trainees from the two universities were included in this study. The mean comfort level of otologic anatomy was rated 4.8 (± 2.2) out of 10. Senior residents possessed more otologic surgical experience (P < 0.001) and higher average comfort when compared to junior residents [6.7 (± 0.7) vs. 3.6 (± 1.9); P = 0.001]. Face and content validities were achieved in all respective domains with no significant difference between the two groups. Overall, respondents believed OtoVIS was a useful tool to learn otologic anatomy with a median score of 10.0 (8.3–10.0) and strongly agreed that OtoVIS should be added to OHNS training with a score of 10.0 (9.3–10.0).ConclusionsOtoVIS achieved both face and content validity as a photorealistic VR otologic simulator for teaching otologic anatomy in the postgraduate setting. As an immersive learning tool, it may supplement trainees’ understanding and residents endorsed its use.Graphical

Shadow-Less Intrinsic Hyperspectral Point Cloud Generation From HSIs and LiDAR

Generating hyperspectral point cloud from hyperspectral images (HSIs) and Light Detection and Ranging (LiDAR) has become more and more common in the remote sensing field and supported various applications. One challenge here is that hyperspectral imaging is a passive imaging method and is suffering from shadows in a natural scene. Intrinsic information recovery can effectively eliminate the spectral variation caused by illumination changes; however, it assumes a uniform light and neglects the shadows in the scene. In this paper, we provide a novel hyperspectral point cloud intrinsic model that can detect the shaded regions and recover reflectance information in them. We first estimate the global illumination of the scene using an intrinsic information recovery method. Then, we perform supervoxel segmentation on hyperspectral point cloud to calculate the blocking relation of supervoxels and therefore accurately detect shaded regions. Finally, we estimate the illumination and reflectance of shaded regions based on an illumination invariant spectral prior. The experimental results show that the proposed method can effectively detect shaded areas and robustly generate shadow-less intrinsic hyperspectral point cloud.

Динамика Ланжевена в стохастической трассировке лучей: выбор фазового пространства и ограничения на вариацию трассы

The main computationally extensive task of realistic computer graphics is the calculation of global illumination. The work investigates the speed of the convergence of lighting simulation using Monte Carlo integration based on the Langevin equation. The paper presents the second part of the work, which analyses the choice of the phase space, restrictions on the possible variations of light path, and the calculation of the probability density of the transition proposal. It is shown how these aspects affect convergence.